- Dehydrative Coupling of Benzylic Alcohols Catalyzed by Br?nsted Acid/Lewis Base
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Traditional cross-coupling reactions show some disadvantages like the use of organohalides or the production of stoichiometric amounts of waste. The dehydrative homo- or heterocoupling of alcohols therefore arises as an interesting approach for a highly atom-economical formation of carbon–carbon bonds, since water is produced as the only by-product. We herein report a simple and direct, metal-free protocol for the synthesis of olefins by applying catalytic amounts of a sulfonic acid and triphenylphosphane under air. A variety of olefins could be synthesized from benzylic alcohols under relatively mild conditions. Additionally, dehydrative hydroarylation of benzylic alcohols with electron-rich arenes was possible by using only Br?nsted acid under otherwise same reaction conditions. We could show that phosphane additives are essential to overcome oligomerization as main side reaction by the occupancy of the reactive carbocation intermediate.
- B?ldl, Marlene,Fleischer, Ivana
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p. 5856 - 5861
(2019/08/07)
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- Transition-Metal-Free Sulfuration/Annulation of Alkenes: Economical Access to Thiophenes Enabled by the Cleavage of Multiple C-H Bonds
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A novel, atom economical, and transition-metal-free strategy for the synthesis of thiophenes from substituted buta-1-enes with potassium sulfide has been presented. The reaction achieves double C-S bond formations via cleavage of multiple C-H bonds and provides an efficient approach to access various functionalized thiophenes. Moreover, the strategy can also be used for the synthesis of thiophenes from 1,4-diaryl-1,3-dienes. Mechanistically, DMSO plays a role of oxidant and S3?- in situ generated from K2S is involved.
- Chen, Liang,Min, Hao,Zeng, Weilan,Zhu, Xiaoming,Liang, Yun,Deng, Guobo,Yang, Yuan
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supporting information
p. 7392 - 7395
(2019/01/03)
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- One-pot synthesis of 1,3-diaryl but-1-enes from 1-arylethanols over Snβ zeolite
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An environmentally benign catalytic protocol has been successfully developed for the one-pot synthesis of 1,3-diaryl but-1-enes from 1-arylethanols via dehydration of 1-arylethanols followed by head-to-tail dimerization of vinylarenes over heterogeneous c
- Mameda, Naresh,Gajula, Krishna Sai,Peraka, Swamy,Kodumuri, Srujana,Chevella, Durgaiah,Banothu, Rammurthy,Amrutham, Vasu,Nama, Narender
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- Highly efficient TfOH-catalyzed head-to-tail dimerization of vinylarenes
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A convenient and efficient TfOH-catalyzed head-to-tail dimerization of vinylarenes has been realized under mild conditions. The present protocol provides an attractive approach to a diverse range of higher olefins in good to excellent yields.
- Yue, Hui-Lan,Zhao, Xiao-Hui,Jiang, Lei,Shao, Yun,Mei, Li-Juan
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p. 179 - 186
(2016/02/23)
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- Efficient hydroarylation and hydroalkenylation of vinylarenes by Br?nsted acid catalysis
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Br?nsted acid Tf2NH alone catalyzed Friedel-Crafts-type hydroarylation and head-to-tail hydroalkenylation of vinylarenes under mild reaction conditions have been realized, providing a readily scalable, metal-free, and practical access to the 1,1-diarylalkane scaffolds and trans-1,3-diaryl-1-butenes in high yields and excellent regioselectivities.
- Liu, Muwen,Zhang, Jinlong,Zhou, Hui,Yang, Huameng,Xia, Chungu,Jiang, Gaoxi
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p. 76780 - 76784
(2016/09/03)
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- Iodine-Promoted Metal-Free Head-to-Tail Dimerization of Styrenes Affording 1,3-Diarylbut-1-enes
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A convenient and efficient iodine-mediated head-to-tail dimerization of styrenes to produce the corresponding dimers in the presence of triethyl phosphite is reported. The advantages of the present protocol are metal-free conditions, short reaction time, simplicity, and high efficiency.
- Wang, Dingyi,Fang, Yanjiao,Xie, Qihuang,Yan, Zhaohua,Lin, Sen,Guo, Shengmei
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supporting information
p. 2815 - 2818
(2016/12/16)
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- Calcium(II) catalyzed regioselective dehydrative cross-coupling reactions: Practical synthesis of internal alkenes and benzopyrans
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A simple and operationally easy protocol for the regioselective synthesis of internal alkenes through a dehydrative cross-coupling and direct coupling procedure has been described using the environmentally benign Ca(II) catalyst. Several alkenes and alcohols underwent the coupling reaction under solvent-free conditions in a short time to produce the desired alkenes. This method is further extended to show the application in the synthesis of novel benzopyran molecules through a cascade strategy.
- Yaragorla, Srinivasarao,Pareek, Abhishek,Dada, Ravikrishna,Almansour, Abdulrahman I.,Arumugam, Natarajan
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supporting information
p. 5841 - 5845
(2016/12/14)
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- Highly efficient catalytic dimerization of styrenes via cationic Palladium(II) complexes
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A highly efficient head-to-tail dimerization of a styrene was developed using a cationic palladium(II)-catalyzed selective C-C bond forming reaction. The complex [AllylPd(PPh3)]+OTf-, which is believed to generate 'palladium hydride' (Pd-H), catalyzed the dimerization of various styrenes in excellent yields as single isomers. This Pd(II)-catalyzed reaction provides a new economical C-C bond forming method. Copyright
- Choi, Ji Hye,Kwon, Jae Kwan,Rajanbabu,Lim, Hwan Jung
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supporting information
p. 3633 - 3638
(2014/01/06)
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- Chemoselective hydroamination of vinyl arenes catalyzed by an NHC-amidate-alkoxide Pd(II) complex and p-TsOH
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The hydroamination of various substituted vinyl arenes with benzenesulfonamide was explored using an NHC-amidate-alkoxide palladium catalyst in conjunction with p-TsOH. Utilizing halide-substituted and electron-rich vinyl arenes, this methodology selectively furnished the cross-coupled hydroamination products in moderate to excellent yields in a Markovnikov fashion while greatly reducing undesired acid-catalyzed homocoupling of the vinyl arenes. Electron-rich vinyl arenes typically required milder conditions than electron-poor ones. While most effective for para-substituted substrates, the catalyst system also furnished the desired products from ortho- and meta-substituted vinyl arenes with high chemoselectivities.
- Giles, Richard,O'Neill, Justin,Lee, Joo Ho,Chiu, Michael K.,Jung, Kyung Woon
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p. 4083 - 4085
(2013/07/25)
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- Highly efficient Pd(acac)2/TFA catalyzed head-to-tail dimerization of vinylarenes at room temperature
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Pd(acac)2 catalyzed dimerization of vinylarenes to form dimers under mild condition with excellent yields and stereoselectivities. In particular, the use of TFA highly promoted the activity and selectivity of the dimerization. The studies on mechanism for the reaction displayed clearly that the dimerization of styrenes is 100% atom economic reaction.
- Ma, Hengchang,Sun, Qiangsheng,Li, Wenfeng,Wang, Jinxia,Zhang, Zhe,Yang, Yaoxia,Lei, Ziqiang
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scheme or table
p. 1569 - 1573
(2011/05/05)
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- Iron-catalyzed stereospecific olefin synthesis by direct coupling of alcohols and alkenes with alcohols
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Chemical equations presented. An efficient Fe(III)-catalyzed direct coupling of alkenes with alcohols and cross-coupling of alcohols with alcohols to give the corresponding substituted (E)-alkenes stereospecifically is demonstrated. Additionally, this reaction could be scaled up. The kinetic isotope effect (KIE) experiments indicated a typical secondary isotope effect in this process. Although benzylic alcohols were effective substrates, mild conditions, atom efficiency, environmental soundness, and stereospecificity are features that make this procedure very attractive.
- Liu, Zhong-Quan,Zhang, Yuexia,Zhao, Lixing,Li, Zejiang,Wang, Jiantao,Li, Huajie,Wu, Long-Min
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supporting information; experimental part
p. 2208 - 2211
(2011/06/20)
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- A new type of carbonylation of styrenes catalyzed by Pd(OAc)2 combined with molybdovanadophosphate
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A new type of carbonylation of styrenes was achieved under a 1:1 mixture of CO (0.5 atm) and O2 (0.5 atm) in the presence of Pd(OAc)2 combined with H5PMo10V2O40 nH 2O to give 4-methyl-2-phenylnaphthalen-1(4H)-one in 78% yield. Various substituted styrenes were also carbonylated to the corresponding substituted arylnaphthalen-l(4H)-ones in moderate yields. The reaction was found to proceed in two stages involving the head-to-tail dimerization of styrenes, followed by carbonylation of the resulting dimers. Styrenes were efficiently dimerized under air (1 atm) in the absence of CO even at room temperature to produce head-to-tail dimers in good yields.
- Yamada, Shingo,Obora, Yasushi,Sakaguchi, Satoshi,Ishii, Yasutaka
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experimental part
p. 1194 - 1198
(2009/06/06)
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- Bronsted acid-catalyzed benzylation of 1,3-dicarbonyl derivatives
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The direct alkylation of 1,3-dicarbonyl compounds with benzylic alcohols is shown to be efficiently catalyzed by simple Bronsted acids such as triflic acid (TfOH) and p-toluenesulfonic acid (PTS) to give rise to monoalkylated dicarbonyl derivatives in high yields. In the absence of the nucleophile, substituted alkenes, generated through a formal dimerization reaction, are obtained. The reactions are carried out in air using undried solvents, with water being the only side product of the process.
- Sanz, Roberto,Miguel, Delia,Martinez, Alberto,Alvarez-Gutierrez, Julia M.,Rodriguez, Felix
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p. 2027 - 2030
(2008/02/02)
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- Palladium-catalysed dimerization of vinylarenes using indium triflate as an effective co-catalyst
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A palladium-indium triflate catalyst was found to be much more active for the dimerization of vinylarenes compared with generally used cationic palladium(II) catalysts.
- Tsuchimoto, Teruhisa,Kamiyama, Susumu,Negoro, Ryoju,Shirakawa, Eiji,Kawakami, Yusuke
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p. 852 - 853
(2007/10/03)
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